Nuclear mangetic resonance (NMR) spectroscopy is being used to investigate the chemical conjugation of specific 13C-labeled benzo(a)pyrene oxides to gluthathione, enzymatically and non-enzymatically. The regiospecificity and stereospecificity of the reaction will be determined. Mechanistic elaboration of the binding process is important in understanding, preventing, and predicting the mechanism(s) of action of such compounds. Several specifically 13C-labeled benzo(a)pyrene derivatives have been obtained and studies of their chemical and biological conjugation have been initiated.